I have done a lot of robotics and was looking for a good FPGA project, so I decided to make a robot controller. My initial plans are to implement obstacle avoidance and line following.
For distance sensing, I am using MAXSonar-EZ1 sensors. These sensors are very easy to use with an FPGA because they can provide distance as a pulse width output. This means all I have to do is time a pulse. Another benefit of this is that I can reuse this code to receive PWM from an RC receiver.